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CHAPTER XXXIV.
TOPAZ.
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HE name of this stone is derived from the Greek Topazios—a
word which appears to have been sometimes wrongly applied to the
Chrysolite or Peridot. This was probably the ancient classic gem,
called in Hebrew Pittdoh by Professor Aaron Pick, and Pitdah by Genesius (according to the Massoreth), the latter of whom imagines that it is derived from the Sanscrit pita (palej, and that the Greek Topazios s a transposition from Pitdoh to Tipdoh. The
ancient mineralogists described this as a pale yellowish or greenish
gem found in an island of the Red Sea. Boetius says it is of a "
diluted green colour with yellowness added to it." Among the virtues
then attributed to it we read that "the Topaz calms anacreontic
temperaments."
Under the general name of Topaz modern mineralogists include three distinct stones—(i) the true Topaz ; (2) the Yellow Sapphire, or the Oriental Topaz ; and (3) the Occidental or False Topaz. The second is a yellow Corundum, and the third is only a variety of Scotch Quartz.
The
true Topaz presents a variety of colours, from clear white, when it has
been occasionally palmed off as a Diamond, ranging through all shades
of light blue and light green to rose pink, orange, and straw yellow. A pink
colour is frequently obtained by subjecting the sherry-coloured Topazes
to a moderate temperature. The instability of colour in certain Topazes
is attested by the bleaching which they suffer on exposure to sunlight.
Crystals of Topaz are remarkable for their pyro-electricity — in other words they become electric on exposure to heat.
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